This invention relates to flow regulating valves and also to those furnished with check valves therein and capable of regulating fluid flow in one direction and permitting free flow in the opposite direction, the latter can be used for controlling piston speed of hydraulic or pneumatic cylinders.
As illustrated in a schematic view in FIG. 1, two of such speed control valves 1 and 1' are generally connected to the opposite ends of cylinder 2 with each inlet port of controlled flow 1a and 1a' respectively, and each inlet port of free flow 1b and 1b' is connected to the source of the compressed air such as compressor 4 through a change valve 3.
When the compressed air is introduced to the right side control valve 1', the air flows into the right side chamber of the cylinder 2 freely through a check valve 1c' and pushes the piston 2' toward the left, and the air in the left side chamber is discharged through a regulating valve 1d of the left side control valve 1 and the change valve 3, so that the speed of the piston 2' can be controlled by the regulating valve 1d,
In the similar way, when the compressed air line is changed to the left side control valve 1 by shifting the change valve 3, the air flows into the left side chamber of the cylinder 2 freely through a check valve 1c, and pushes the piston 2' toward the right, and the speed of the piston 2' can be controlled by a regulating valve 1d'.
In the conventional flow regulating valves, the threaded portion of the valve stem engages with the threaded hole of the valve body and the handle portion of the stem is projecting out from the valve body, so that the shape of the valve is made complicated. Further, when the size of the valve is made small, the diameter of valve stem also becomes small, so that the fine adjustment of the flow may become difficult.
Recently, very small size of about several mm diameter power cylinders are required in the field of electronic industries, therefore in connection with this, small size speed control valves may be also required, but it is considered difficult to obtain such speed control valves with the ordinary valve construction, by the reason as mentioned above.
It is an object of this invention to provide a flow regulating valve of very compact form. Another object of this invention is to provide a flow regulating valve capable of fine adjustment of the flow rate even when the valve is made very small size.